We currently do scope analysis for stylesheets that are added to the end of the active stylesheet list to avoid unnecessary style
recalcs and StyleResolver rebuilding. However it is somewhat common to insert <style> elements dynamically to positions other than last.
In this case we currently simply force full style recalc. We should do scope analysis and partial style recalcs also in these cases.

Check if there have been insertions to the stylesheet list. If so we need to reset
the StyleResolver (to handle rule position changes) but don't need to force full
style recalc. Do scope analysis for inserted stylesheets as well.